A state plan to reform property taxes for motor vehicles would offer lots of tax breaks to the rich.

Just about everyone agrees that the way cities and towns tax cars and trucks is unfair.

For the same model, same year, same mileage, you'll pay nearly seven times as much in property taxes in Hartford as you do in Greenwich, where tax rates are low because the value of houses is so high.

"A car is a car is a car," said Senate President Pro Tem Martin Looney. No, he's not defying sacred American culture; he's just pointing out that unlike houses, vehicles have the same value wherever they happen to be.

"And it really doesn't make sense to have the taxation be different," Looney said.

Schemes to address this supposed inequity have come and gone in the state legislature over the years, including ones from Gov. Dannel P. Malloy and Gov. M. Jodi Rell.

This could be the year it happens, as the latest plan — not from Malloy but from Democrats in the legislature — appears to be a serious part of the backroom state budget talks now underway.

Unfortunately the plan has some big problems even beyond the fact that it would cost state taxpayers at least $85 million a year at a time when the state is deep in a hole.

The state would cap the rate cities and towns could levy at 29.36 mills, or $29.36 per $1,000 of assessed value. That's this year's average across the state. Because many cities and towns levy a higher rate — Hartford is the highest at 74.29 mills — the state would make up the difference, ensuring that all local governments remained whole.

The money would come from the state sales tax, as part of a broader local property tax relief plan that would divert one-half of 1 percentage point of the sales tax and send more aid to targeted cities and towns.

The car tax reform is simple enough to understand. But its effects are not at all simple to figure out, and its fairness is questionable when you look at the details closely. Lots of struggling people would subsidize lots of rich people.

Looney and other supporters see a triple virtue in the car tax plan. It not only would equalize the tax that motorists pay across the state, but also would help residents of the poorest cities, and it would help those cities attract middle-class residents, stabilizing their whole regions.

Hartford, New Haven, Bridgeport, Waterbury and New Britain all have tax rates in the top eight among all 169 cities and towns, because each of those high-poverty cities has low property values and needs to maintain a higher tax rate to raise the same amount as a richer town whose property is worth more.

The eight towns with the lowest tax rates are all tony places in Fairfield and Litchfield counties — Greenwich, Sharon, Darien and Roxbury among them — where the tax rates are in the 10- to 15-mill range. That gives car owners in those towns a cheap ride.

"For the most part it looks like the towns with the high mill rate, there is a high rate of need," Looney said.

He's right, for the most part. But the plan would give plenty of tax breaks to people in rich towns, too. Among the 25 municipalities with tax rates over 35 mills for the current tax year, six had median household incomes over $85,000 a year in 2012 — well above the state average of $69,519.

That includes Simsbury, with a median income of $117,577, according to data compiled by the Connecticut Economic Resource Center, and Glastonbury, with a median of $106,872. All those soccer fields add up in cost if you have too little local industry.

What this means is that the family in Simsbury with a Mercedes, a BMW and a Volvo, worth a total of $82,000 — not outlandish in that town — would have seen its car tax bill drop by $446, from $2,132 to $1,686, if the plan had been in effect this year.

Simsbury would collect that $446 from the state. That means a guy in Windsor Locks buying a hammer would be sending money to that rich family in Simsbury.

Supporters of the reform will say that's an extreme example. Most people benefiting from the car tax would either be poor or middle class, and most breaks would be smaller than our Simsbury family's $446 a year.

And they would say the leakage of aid to rich people is a necessary evil for the greater good.

All true. But the leakage adds up fast. Remember, the car tax plan is a break for taxpayers in high-tax towns, not for the towns as a whole. That means thousands of very comfortable people who live in high-tax towns, such as Vernon and Wethersfield, will pull in a subsidy from people and businesses paying the state sales tax.

Is there a better way to get there? Perhaps the state could set a mandatory rate for car taxes rather than a ceiling, and towns would adjust accordingly. The state could then send more aid to the poorer towns that needed it most. But that would never fly politically and would bring its own distortions, for example, hurting motorists who chose to keep an old car on the road longer.

Making wealthier people pay higher car tax rates would be a bloody mess.

Towns can also set their tax rates lower for vehicles on their own, and the state could then choose to send them more money, or not. After Stamford and New London set separate motor vehicle rates, the state Office of Policy and Management sought an opinion on whether they could do that from then-Attorney General Richard Blumenthal, who said there's no law against it.

"The statute is ambiguous and should be clarified by the General Assembly," Blumenthal wrote in 2006.

In West Hartford, another high-tax town with wealthy residents, Joseph Dakers, director in the assessment office, is watching closely. He's already calculated that — before the extra state payments — the change would cut the town's take from motor vehicles by $3.8 million, to $12.2 million, from the owners of 47,215 cars and trucks.

That's $80 per vehicle. Not a lot, but again, it adds up fast. We do welfare for the rich all the time, but we like it better when it advances a laser-targeted social good, like technology research, homeownership or filling up downtown Hartford apartments.

The property tax plan aimed at sending more money to cities has the honored number of Senate Bill 1, reflecting Looney's commitment to it. Malloy is not behind it because he wants that sales tax money to go toward his massive transportation infrastructure plan, sources told the Connecticut Mirror.

Some of the plan, like higher payments from the state in lieu of taxes for colleges and hospitals, works well, especially as those institutions spread wildly. Taxing those institutions when they take over houses and businesses might also make sense.